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## Re: How to average to find 'circular' symmetry in a SQUARE matrix?

**From**: |
Robert A. Macy |

**Subject**: |
Re: How to average to find 'circular' symmetry in a SQUARE matrix? |

**Date**: |
Mon, 15 Jan 2007 17:31:51 -0800 |

Doug,
Yes, 1 degree, 10 degrees, or 127 degrees, image that is
represented by x-y data set is perfectly axisymmetric.
How do I use polar notation to average?
- Robert -
Chris,
How do I use 2D Lagrange interpolation? Sounds exactly
what I need, but didn't find any functions that looked like
it would do that.
What were you using it on?
- Robert -
From: "Chris Zarowski" <address@hidden>
>* Maybe I misunderstand, but it sounds like*
>* you need to do interpolation in 2D.*
>
>* There is a 2D form of Lagrange interpolation*
>* that is perhaps the easiest thing.*
>
>* The idea is to interpolate over a desired circle*
>* (appropriately centered), and average the interpolants.*
>
>* I actually had this problem in processing some*
>* grey-scale images from a thin-film optics experiment.*
>* *
>* Chris Z*
On Mon, 15 Jan 2007 19:06:24 -0500
Doug Stewart <address@hidden> wrote:
>* Hi Robert*
>* *
>* Do you mean by rotational symmetry that if you rotate*
>* it 10 deg ( or *
>* 20 or 30 etc.) it still has symmetry or do you mean*
>* rotate by 90 deg. steps.*
>* *
>* *
>* If it is by any deg. then maybe you could use polar*
>* notation?*
>* *
>* Doug Stewart*